A heat-stable oil-in-water emulsion and a process for its manufacture

Abstract: The invention concerns a heat-stable oil-in-water emulsion containing from 5 to 75% fat, from 0.1 to 10% vinegar, from 0.1 to 5% DATEM and from 0.1 to 10% protein salt and/or sugar, aroma and water and having a pH of from 3 to 8.

Description: This invention concerns a heat-stable, oil-in-water emulsion containing between 5 and 75% fat, between 0.1 and 10% vinegar, salt and/or sugar, aroma and water. The invention relates further to a process for the manufacture of said emulsion. The emulsions may be used in the production of emulsified food products. Japanese Patent Application of Asahi Foods KK No. 61209562 describes the manufacture of an oil-in-water emulsified composition containing oil, fat, protein and a mixture of three different emulsifiers. The composition is heat-stable but, because of the three emulsifiers, is expensive. It is also less accepted by consumers and has a bad taste due to the presence of lecithin. An object of this invention is to provide a heat-stable, oil-in-water emulsion containing fat and an emulsifier which is not egg yolk and which has good stability, viscosity, smoothness, taste and colour properties. Accordingly, this invention provides a heat-stable, oil-in-water emulsion according to the preamble of claim 1 and further containing from 0.1 to 5% diacetyl tartaric acid ester of monoglyceride (referred to as DATEM in this specification) and from 0.1 to 10% protein and having a pH of 3 to 8. All the percentages are given in weight on a dry basis. DATEM is known in the art as an emulsifier, but if used alone, the obtained oil-in-water emulsion, although heat-stable, is too liquid and does not yield a product with the required physical properties, such as viscosity, to be successfully launched on the market. Similarly, proteins like casein are also known for their emulsifying function, but if used alone, the obtained oil-in-water emulsion usually would not be heat-stable. Hence, although the emulsion might have high viscosity, it would not lead to products which have smooth texture and acceptable emulsion stability. Surprisingly however, DATEM and protein when combined in an oil-in-water emulsion lead to a synergistic effect in that the emulsion is heat-stable and also has very good physical properties, such as emulsion stability, smoothness and viscosity. Preferably, the amount of DATEM used is from 2 to 3%. Preferably the amount of protein used is from 2 to 5%. The type of protein used is not critical: the protein may be selected from skim milk powder, casein, whey protein, pea protein and soya protein. Skim milk powder is preferred because it is significantly lower in price and better in colour and taste than the other mentioned proteins. From a general point of view, the obtained emulsion is heat-stable, meaning that it can withstand UHT-treatment (less than one min at 140°C) or sterilization at 110°C for 10 minutes. The oil-in-water emulsion may be a mayonnaise-product, a spread or a sauce. By oil, we mean all food grade oils such as soy-bean oil, sunflower oil, grapeseed oil, peanut oil, butter oil and also butter fat. For the mayonnaise and spread, the emulsion is produced without heat-treatment. On the contrary, for a sauce, the production process includes heat-treatment, such as pasteurization or sterilization. For a mayonnaise-like product, i.e. a product with a high fat content, the product preferably contains from 50 to 75% oil and has a pH of 3 to 5. Such a product has a viscosity comparable to that of normal mayonnaise, and has a creamy appearance, good emulsion stability and a smooth texture. However, unlike mayonnaise, the product does not contain egg yolk. For a spread, the oil content is preferably from 20 to 75%. In the case of a sauce, the emulsion preferably contains from 5 to 50% oil and from 1 to 30% butter. The amount of salt and sugar used is preferably from 0,1-3% salt and 0,1-30% sugar. Aromas and ingredients which lead to savoury or sweet products may also be added. The emulsion may be prepared by mixing together the aqueous phase ingredients, such as water, salt and/or sugar, aroma, DATEM and proteins. After that, the oil is slowly added and the obtained mixture is emulsified. After emulsification, the vinegar is added. Usually the vinegar must be added after emulsification, otherwise the obtained emulsion is thin and has a sandy texture, with no or reduced emulsion stability. In the case of the manufacture of a sauce, an homogenization takes place after the vinegar has been added. Examples are now described by way of illustration only. In the examples, physical stability of mayonnaises is measured by subjecting it to centrifugation and observing the separation of oil and serum. Heat stability of mayonnaises is tested by heating 10 ml of emulsion in a test tube in a boiling water bath for 30 minutes. Heat-stability of sauces is tested by UHT treating (140°C for 10 sec.) or sterilising (110°C for 10 min). After cooling, a 100 ml sample is reheated in a microwave oven (650 watt) at maximum setting for 2 min. Alternatively 500 ml is reheated to boiling point in a glass beaker on a kitchen hot plate. The emulsions are judged visually and emulsions showing protein coagulation or oil separation are considered unstable. Structural properties such as roughness and smoothness are determined from the visual appearance of the emulsion. Expert opinion is used. Comparative Examples 1 to 4: Mayonnaise Water, salt (0.8%), sugar (1%), mustard aroma (0.1%) and 2% skim milk powder are mixed (3000 rev/min for 2 min) in a 2 kg Stephan mixer. The oil is added slowly (30 seconds) and the mixture is emulsified at 3000 rev/min for 1.5 min (0.5 bar vacuum). The results are given here-in-below with 3 different proteins and DATEM separately (the percentage of each component is always 2, except for Example 2 where it is 1%). Example Emulsifier Protein Viscosity Stability after centrifugation Structure (mPas) serum/oil (ml) 1 - skim milk powder 2420 2.2/0 rough 2 - caseinate 2700 2.5/0 rough 3 - soya protein 960 2.5/0.1 smooth 4 DATEM - 325 0.5/0 smooth The viscosity is measured using a Bohlin CS viscometer. In each case, (except DATEM) the stability is bad corresponding to a release of more than 2 ml of serum, or a release of any oil, per 8 ml of emulsion. A viscosity of 1500 mPa is considered as acceptable, which is the case for examples 1 and 2, but the product structures are rough. The compositions are thermal instabile except with DATEM alone. Examples 5 to 7: Mayonnaise The procedure mentioned for examples 1 to 4 is repeated, but instead of adding DATEM alone or protein alone, DATEM and protein are added together. The results are given in the following table Example Emulsifier Protein Viscosity (mPas) Stability after centrifugation Structure (mPas) serum/oil (ml) 5 DATEM skim milk powder 4290 1.0/0 smooth 6 DATEM caseinate 3920 1.5/0 smooth 7 DATEM soya protein 1540 2.2/0 smooth Each emulsion contains 2% DATEM and 2% proteins. (except for example 6 which contains 1% caseinate). The stability of these compositions is markedly improved as can be seen from the reduced serum and oil separation after centrifugation. In all three examples the structures are smooth and the viscosity is markedly increased compared to examples 1 to 4 when only the single emulsifiers are used. All these compositions are heat-stable. Example 8: Mayonnaise without egg yolk For a 30 kg batch of mayonnaise, 4% skim milk powder, 6.3% DATEM paste (2% DATEM + 4.3% water), salt, sugar and spices are dissolved in 10.2 % water. Sunflower oil, 68%, is added slowly under vacuum and emulsified. Then 7% vinegar (11% acetic acid) is added and mixed. The stability, viscosity and texture are similar to that of a mayonnaise made with egg yolk, while the taste is clean and without off-taste. Example 9: Sweet mayonnaise spread For a 30 kg batch of spread containing 14.2% sugar, 2.5% cacao, 4% hazelnut spread, 3% skim milk powder and 6.3% DATEM paste, all the ingredients except the oil and vinegar are dissolved in 9.8% of water. The oil, 57%, and 2.5% vinegar are added as described above. The product has a very high viscosity, with smooth and stable texture and sweet chocolate taste. Example 10; Hollandaise Sauce without egg yolk For a 4 kg batch of Hollandaise Sauce containing no egg yolk, 0.5% skim milk powder, 2.5% DATEM paste and the dry materials (sugar, starch, xanthan, spices), are dissolved in 64% water. The butter, 10% and 12.5% soya oil are heated to 50°C and emulsified with the water phase after which 0.3% vinegar is added. It is then homogenized and the product is either UHT treated (140°C, 6 sec) or sterilised (110°C, 10 min). After cooling the products are reheated in a microwave oven or hot plate as described above. The product has similar viscosity, heat stability and taste to that made with 4% egg yolk modified by Phospholipase A2 enzyme. Similar results as above are obtained with soya protein or caseinate in combination with DATEM. The emulsion made with DATEM alone as emulsifier was heat-stable but too thin, and that made with skim milk powder alone had high viscosity, but was not heat-stable.

Claims: A heat-stable oil-in-water emulsion containing from 5 to 75% fat, from 0.1 to 10% vinegar, salt and/or sugar, aroma and water, characterized in that it further contains from 0.1 to 5% DATEM and from 0.1 to 10% protein and has a pH of from 3 to 8. A heat-stable oil-in-water emulsion according to claim 1, characterised in that it contains from 2 to 3% DATEM and from 2 to 5% protein. A heat-stable oil-in-water emulsion according to claim 1 or 2, characterized in that the protein is selected from skim milk powder, casein, whey protein, pea protein and soya protein, or mixtures thereof. A heat-stable oil-in-water emulsion according to any of claims 1 to 3, characterized in that it is mayonnaise-like, contains from 50 to 75% oil and has a pH of from 3 to 5. A heat-stable oil-in-water emulsion according to any of claims 1 to 3, characterized in that it is a sauce, contains from 5 to 50% oil and from 1 to 30% butter. A process for the manufacture of a heat-stable oil-in-water emulsion according to any of claims 1 to 4, wherein water, salt and/or sugar, aroma, DATEM and protein are mixed together, oil is added and the obtained mixture is emulsified, characterized in that the vinegar is added after said emulsification. A process for the manufacture of a heat-stable oil-in-water emulsion according to claim 5 wherein water, salt and/or sugar, aroma, DATEM and protein are mixed together, oil is added and the obtained mixture is emulsified and homogenized, characterized in that the vinegar is added after said emulsification.

Inventors: CAMPBELL LYDIA, TRUECK HANS UWE, CAMPBELL, LYDIA, TRUECK, HANS UWE
Applicants: NESTLE SA, SOCIETE DES PRODUITS NESTLE S.A.
Application year: 1994
Main classification: A23L1
IPC codes: A23D7, A23L1